The goal of this project is to develop a primate model of an upper extremity neuromuscularstimulation system controlled by means of intra-cortical recording electrodes. Individuals with spinal cord injury become paralyzed because they have lost the ability to activate their muscles. These patients' muscles can still be made to contract if they are activated by means of electrical stimuli applied directly to the muscle or nerves. Likewise, the areas of the brain that normally control movement are still active, but their connection to the muscles has been lost as a result of the injury. Researchers at Case Western Reserve University (CWRU) have demonstrated that implanted functional electrical stimulation (FES) neuroprostheses can be used to restore grasp functions to individuals with tetraplegia. Although remarkable, these systems are limited to pre-programmed grasp patterns, and require considerable conscious attention. A more natural control system, with more degrees of freedom could provide greatly improved function. At Northwestern, we have developed methods to predict the activity of arm and hand muscles during grasping movements based on micro-electrode recordings from the brain of a monkey. From a single, chronicallyimplanted array of electrodes, predictionscan be made of the activity of shoulder, arm and hand muscles. This type of electrode has yielded maintained recordings for periods in excess of 3 years, and it has recently been approved for experimental use in human patients. We believe that intra-cortical recordings like these provide the potential for simultaneouscontrol of multipledegrees of freedom through natural thought processes. By combining the strengths of the Northwestern and CWRU groups, we propose to develop a brain-computer interface adequate for controlling a neuroprosthesis. The development of a primate model of this neuroprosthetic system would be a major step toward its implementation in human patients. This application includes the following specific aims: 1) We propose to use a 100-electrode array implanted in the primary motor cortex of a mnkey to provide the input to a set of decoders designed to produce real-time predictions of the activity of particular hand muscles. 2) We propose to use the control algorithms developed in aim 1 and an implanted FES prosthesis to restore grasp followingtemporary muscle paralysis induced by a pharmacological nerve block. 3) We propose to develop these control algorithms without the use of initial EMG measurements, as would be necessary in order to implement the system for a patient.